Refrigeration systems such as centrifugal chillers, utilize low pressure refrigerants such as CFC-11, CFC-113, HCFC-123 and multi-pressure refrigerants such as CFC-114 and HFC-245fa to operate at, e.g., less than atmospheric pressure, either at all times or under a set of operating or stand-down conditions. Since the chillers are operating at subatmospheric pressures, air and moisture may leak into the machine through these low pressure areas. Once the air and moisture and other non-condensables enter the chiller, the non-condensables accumulate in the condenser portion of the chiller during machine operation. The non-condensable gases in the condenser reduce the ability of the condenser to condense refrigerant, which in turn results in an increased condenser pressure, and thereby results in lower chiller efficiency and capacity.